Truth will out

Possible interpretation: In the end, what is true will come to be known. The truth always appears eventually, despite all efforts to hide it. It is impossible to keep something secret forever.

Note: There is another saying with the same form: "Murder will out."

Origin: This saying was already recorded in England by the 15th century; and it appears in Shakespeare's Merchant of Venice (1596): "Truth will come to light; murder cannot be hid long; a man's son may, but in the end truth will out."

truth (noun): what is factual; what is in accordance with realityout (verb): come out; go out; emerge